The present invention relates to a door opener for a roll-type door in a cargo van, and in particular to such an opener that maximizes the usable interior space of the cargo van.
Ballyns U.S. Pat. No. 4,860,813 discloses a door opener for a roll-up door in a cargo van. In the disclosed system, the door is coupled via flexible winding straps to a drum mounted on a rotatable shaft inside the cargo van above the door opening. A motor is also mounted inside the cargo van above the door opening to rotate the drum and thereby to control the position of the door.
This approach requires both the rotatable shaft and the motor to be positioned within the cargo van above the door opening, and this requirement has drawbacks in many applications. In particular, if a conventionally sized motor is used, in at least some cases the size requirements for the rotatable shaft and the motor for driving the shaft are such that the top of the door opening must be placed at a lower than optimal position in the cargo van. Alternatively, if this disadvantage is to be avoided, a non-standard, relatively expensive motor may be required.
The present invention is directed to an improved door opener that avoids these disadvantages of the prior art.